Synergistic cytotoxic effects of tamoxifen and black cohosh on MCF-7 and MDA-MB-231 human breast cancer cells: an in vitro study

Breast cancer cell cultures were exposed to different concentrations of black cohosh, estradiol (E2), and tamoxifen to examine the effect on cell proliferation; cytotoxicity was assessed by using sulforhodamine B (SRB) dye solution. E2 (10(-10) - 10(-8) mol/L) markedly stimulated the proliferation of MCF-7 cells (p < 0.01). Tamoxifen stimulated MCF-7 cell proliferation at 10(-6) mol/L and 10(-5) mol/L (p < 0.005) but inhibited in a dose-dependent fashion the proliferative effect of E2 (p < 0.001). Black cohosh alone did not show any stimulatory effect, but exhibited a cytotoxic effect, which was significant at 10(3) microg/mL (p < 0.001). Adding black cohosh at 10(0)-10(3) microg/mL to E2 at 10(-9) mol/L also resulted in a dose-dependent inhibition of E2 proliferative effect. Interestingly, the combination of black cohosh (10(0)-10(3) microg/mL) with increasing tamoxifen concentrations further inhibited MCF-7 cell growth. On MDA-MB-231 cells, neither E2 nor tamoxifen displayed any detectable effect. However, black cohosh inhibited MDA-MB-231 cell proliferation at 10(3) microg/mL (p < 0.05), and this inhibitory effect was enhanced by increasing tamoxifen concentrations. This study reveals a cytotoxic effect of black cohosh on both estrogen-sensitive and estrogen-insensitive breast cancer cells and a synergism with tamoxifen for inhibition of cancerous cell growth.     

Cell-specific differences in the susceptibility of potential cellular targets of human origin derived from blood and lung following treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

The induction of cytochrome P4501A (CYP1A1) enzyme activity is one of the best-studied direct effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds and has been shown to be a sensitive biomarker of exposure to polycyclic aromatic hydrocarbons (PAH) in different experimental animal species as well as in humans. TCDD has also been shown to modulate cytokine gene expression in human keratinocytes, including IL-1, TGF- and TFG-₂. In the present studies, the aim was to determine whether different cellular targets of human origin differed in susceptibility to TCDD as measured by CYP1A1 activity and mRNA expression, and whether cytokine gene induction/suppression correlated with TCDD susceptibility. Human airway epithelial cells, alveolar macrophages (AM), peripheral blood monocytes and lymphocytes (PBL) were exposed to 10^-10–10^-7 mol/L TCDD. CYP1A1 enzyme activity was determined by ethoxyresorufin-O-deethylase (EROD) activity, mRNA expression of CYP1A1 was measured by semiquantitative PCR assay. The secretion and/or gene expression of specific cytokines, including IL-6, IL-8, and IL-1 were also examined. Overall, there was a clear correlation between TCDD-induced enzyme activity and CYP1A1 mRNA levels, which were dose-dependently increased in the bronchoepithelial cells and PBL. The human airway epithelial cells (BEAS-S6 cell line and primary cells) appeared to be the most inducible cellular target, with up to 50-fold increases at 10^-8 mol/L TCDD with an EC₅₀ of 3×10^-11 mol/L TCDD. The pokeweed mitogen-activated peripheral blood lymphocytes revealed approximately 5-fold less capacity in CYP1A1 activity, with high interindividual variabilities (EC₅₀ 3×10^-9 mol/L TCDD). In contrast, CYP1A1 enzyme activity in both AM and purified peripheral blood monocytes, which were costimulated with LPS and/or GM-CSF, could not be detected. CYP1A1 mRNA levels, however, were detectable and only marginally enhanced in response to TCDD. The ability of all these cells to express and produce the proinflammatory cytokines IL-6 and IL-8 was neither enhanced nor impaired by TCDD. These results indicate that cell types found in human lung and peripheral blood vary in susceptibility to TCDD, with the lung epithelium being highly susceptible and the alveolar macrophage being nonsusceptible. However, expression and production of specific cytokines such as IL-6 and IL-8, which may potentiate inflammatory processes and/or work as mitogens, does not appear to be influenced by TCDD.     

Acute cytotoxicities of polynuclear aromatic hydrocarbons determined in vitro with the human liver tumor cell line,HepG2

The neutral red in vitro cytotoxicity assay was adapted for use with the human hepatocellular tumor cell line HepG2 to detect the cytotoxic potencies of polynuclear aromatic hydrocarbons (PAHs). Using benzo[a]pyrene (B[a]P) as the representative PAH, it was determined that a 3-day exposure was the most suitable for detecting cytotoxic potency and that preexposure to S g/ ml Arochlor enhanced the sensitivity of the HepG2 cells to the toxicant. Such enhanced sensitivity probably reflected increased metabolic conversion of the B[a]P to active metabolites after culturing the cells in the presence of Arochlor. This was shown by a 3-fold increase in the activity of 7-ethoxycoumarin deethylase, an indicator of mixed-function oxygenase activity. Furthermore, a reduction in sensitivity to B[a]P occurred when the cells were cultured in the presence of -napthoflavone, an inhibitor of aryl hydrocarbon hydroxylase activity. When Arochlor-induced cells were transferred to medium lacking Arochlor, the level of 7-ethoxycoumarin deethylase quickly declined to basal levels. Arochlor-induced cells were also able to detect the cytotoxic potencies of benzo[k]fluoranthene, benzo[b]-fluoranthene, chrysene, benzo[a]anthracene pyrene, phenanthrene, and fluoranthene, whereas fluorene, anthracene, acenaphthene, and acenaphthylene were not cytotoxic.Abbreviations AHH aryl hydrocarbon hydroxylase - 7-EDase 7-ethoxycoumarin O-deethylase - 3-MC 3-methylcholanthrene - MFO mixed function oxidase - NR neutral red - PAH polycyclic aromatic hydrocarbon     

Methylmercury-injury effect on tube formation by cultured human vascular endothelial cells

The effect of methylmercury chloride (MeHg) on growth and tube formation by cultured human umbilical vein endothelial cells (HUVECs) was investigated. HUVECs were collected by enzymatic digestion with collagenase. Precultivation of HUVECs with MeHg at concentrations of 1.0–50.0 mol/L exerted negligible effects on the viable cell number, while the viable cell number was slightly reduced at 100 mol/L and fell to zero at concentrations exceeding 500.0 mol/L MeHg. The viable cell number was depressed in a concentration-dependent manner. Tube formation was studied by culturing the cells on gelled basement membrane matrix (Matrigel). Treatment of HUVECs with 0.1–5.0 mol/L MeHg for 24 h inhibited tube formation dose-dependently. Fetal bovine serum (FBS) increased tube formation in a dose-dependent manner, with half-maximum stimulation of tube formation at approximately 3.4% FBS. The length of tube formation decreased time-dependently at concentrations of 0.1 and 1.0 mol/L MeHg. Pretreatment of Matrigel with 1 mol/L MeHg before the cell seeding reduced the tube formation by HUVECs. These results suggest that the growth and tube formation by HUVECs is susceptible to MeHg cytotoxicity, and that MeHg could be injurious to endothelial cell function.Abbreviations MeHg methylmercury chloride - HUVECs human umbilical vein endothelial cells     

Study of the cytotoxic activity of Styrax camporum extract and its chemical markers,egonol and homoegonol

The benzofuran lignans egonol and homoegonol are found in all species of the genus Styrax. Since natural products are important sources of new anticancer drugs, this study evaluated the cytotoxic activity of a hydroalcoholic extract of the stems of S. camporum (SCHE) and their chemical markers, egonol (EG) and homoegonol (HE), against different tumor cell lines (B16F10, MCF-7, HeLa, HepG2, and MO59J). A normal human cell line (GM07492A) was included. Cytotoxic activity was evaluated at different treatment times (24, 48 and 72 h) using the XTT assay. More effective results were observed after 72 h of treatment. The lowest IC₅₀ values were found for the HepG2 cell line, ranging from 11.2 to 55.0 µg/mL. The combination of EG and HE exerted higher cytotoxic activity than SCHE or treatment with either lignan alone, with the lowest IC₅₀ (13.31 µg/mL) being observed for the MCF-7 line. Furthermore, treatment with these lignans was significantly more cytotoxic for some tumor cell lines compared to the normal cell line, GM07492A, indicating selectivity. These results suggest that these lignans may be used to treat cancer without affecting normal cells.     

Human lymphoblastoid cell lines secreting antibodies with restricted HLA specificity

Peripheral B lymphocytes obtained from three healthy individuals who had been immunized against peripheral blood lymphocytes from appropriate HLA-incompatible donors were transformed by the use of Epstein-Barr virus. The transformed blastoid B cells were repeatedly subcultured by means of cluster picking, and the HLA antibody-producing cultures were identified by testing the culture supernatants by means of the cytotoxicity assay, using the corresponding donor cells. Thus far, four cell lines that secrete cytotoxic HLA antibodies (MP1, 3, 4, and 5) have been established. Specific immunoabsorption experiments revealed that the antibody activity is carried by lambda-type IgM for MP1, by kappa-type IgM for MP3 and MP5, and by both for MP4. Specificity analysis of a panel of HLA-pretyped cells indicated that MP1 detects DQw2, whereas MP5 recognizes B7. The specificity of MP3 was similar to a DQ specificity termed DC5 (probably equivalent to TA10) but not the same. In the case of MP4, both of the lambda-type and kappa-type antibodies appeared to be directed toward new HLA class 11 determinants.Abbreviations used in this paper HLA human major histocompatibility - EBV Epstein-Barr virus - B-LCL Blymphoblastoid cell line - NA not absorbed - PBS phosphate-buffered saline - SPA Sepharose protein A - NRS normal rabbit serum     

Osteotoxicity of cadmium and lead in HOS TE 85 and ROS 17/2.8 cells: relation to metallothionein induction and mitochondrial binding

Epidemiological, experimental and clinical data indicate that cadmium and lead are osteotoxins in man and other species. The relative sensitivities of a clonal human osteosarcoma cell line (HOS TE 85) and a clonal rat osteosarcoma cell line (ROS 17.28) to the cytotoxic effects of cadmium and lead were tested in serum-free media without added growth factors. The rat osteosarcoma cells were more sensitive to cadmium with cytotoxicity and inhibition of proliferation at 0.25 versus 0.75 and 1.0 mol l^– cadmium, respectively, for human osteosarcoma cell lines. The lower sensitivity to cadmium of human osteosarcoma cells is attributed, at least partly, to induction of metallothionein synthesis by cadmium and zinc in this cell line; in the rat osteosarcoma cell line, they do not induce metallothionein synthesis. Human osteosarcoma cells were more sensitive than rat osteosarcoma cells to lead with inhibition (IC₅₀) of proliferation at 4 mol l^– lead and cytotoxicity at 20 versus 6 and over 20 moll^– lead, respectively, for these variables in rat osteosarcoma cells. Both cells lines attained the highest lead concentration in the 15 000 × g (mitochondrial) fraction. The lead in the mitochondrial, microsomal, nuclear and cytosolic fractions of the human cell line did not decrease during 24 h post-washout. Binding of lead was much less stable in the less sensitive rat cells, with 50–100% loss of mitochondrial, microsomal and nuclear lead during 24 h post-washout.     

The differential effects of cadmium exposure on the growth and survival of primary and established cells from fish and mammals

The differential cytotoxic effects of cadmium on fish and mammalian epithelial cells in established and primary culture were assessed by looking at the reduction of the colony-forming ability and reduction in the extent of growth. The influence of medium composition on the toxicity of cadmium was also studied using serum-free and serum-containing media. The experiments using immortalized cell lines showed that mammalian cells were more sensitive than fish cells to cadmium. Both cell types were grown at the same serum concentration. However, using the normal primary system, human epithelial tissue explants showed less sensitivity to cadmium than did similar cultures from rainbow trout. It is likely that cellular mechanisms of cadmium resistance in the different cell types are responsible for these effects. As expected, cadmium proved to be more toxic when tested in serum-free medium. With fish skin primary cultures, reduction of cell numbers was observed at concentrations as low as 5 mol/L in serum-free medium compared to 100 mol/L in serum-containing medium. This was found to be due to the reduction in the activity of free cadmium ions, caused by the presence of serum in the medium. It is concluded that serum-free formulations are probably preferable when testing pollutants in vitro. The results highlight the importance of establishing species-specific pollution tests and standardizing variables.In summary, the results show species and culture media differences in cadmium toxicity and suggest that caution is required when extrapolating results for pollutant effects from one in vitro system to another.Abbreviations CE colony-forming efficiency - EPC epithelioma papulosum cyprini - KGM Clonetics Keratinocyte Growth Medium     

Hypocrellin and hypericin-induced phototoxicity of HL-60 cells: apoptosis or necrosis?

Hypericin and hypocrellin are potential antiviral and antineoplastic agents with multiple modes of light-induced biological activity connected with a production of singlet oxygen and/or excited-state proton transfer and consequent pH drop formation in the drugs environment. In present work light-induced cytotoxicity of hypericin and hypocrellin and mechansim of cell death (apoptosis or necrosis) on human leukemic cell line HL-60 was studied. As a mean for apoptosis detection we used poly (ADP-ribose) polymerase (PARP) as a sensitive marker of early stages of apoptosis. Our results show that exposition of HL-60 cells to hypericin (1 x 10(-5) mol x l(-1)) for 4 hours has no effect on PARP cleavage. However, after 24 and 48 hours of illumination there is evident that hypericin in this concentration cleaved PARP (116 kDa) into two fragments (85 and 25 kDa). Contrary to hypericin, hypocrellin in concentration 1 x 10(-5) mol x l(-1) after 4 hours of illumination cleaved PARP into two fragments typical for apoptosis. In lower concentration (1 x 10(-6) mol x l(-1)) hypocrellin possess also significant cytotoxic activity. Because we detected no fragmentation of PARP in all observed time periods we suggest that cytotoxic effect of hypocrellin in this concentration is due to induction of necrosis. Our results support the hypotesis that the hypericin and hypocrellin has similar mechanism of action and illumination increases cytotoxic effect of both agents.     

Effects of deoxynivalenol (DON) and its microbial biotransformation product deepoxy-deoxynivalenol (DOM-1) on a trout,pig, mouse,and human cell line

Deoxynivalenol (DON), a trichothecene produced by various Fusarium species, is one of the most prevalent food- and feed-associated mycotoxins. The effects of DON and deepoxy-deoxynivalenol (DOM-1) were assessed in five different cell lines from different tissues and species starting from the first line of defense, the trout gill (RTgill-W1) and pig intestinal cells (IPEC-1 and IPEC-J2) over immune cells, as second line of defense (mouse macrophages RAW 264.7) to human liver cells (HepG2). Viability was assessed with a WST-1 assay, except for RTgill-W1, where a neutral red (NR) and sulforhodamine B (SRB) assay was performed. Additionally, more sensitive parameters, such as interleukin-, nitric oxide (NO)-, and albumin-release were determined. Viability was affected by DON at concentrations starting at 10 μmol/L (RTgill-W1), 0.9 μmol/L (IPEC-1), 3.5 μmol/L (IPEC-J2), and 0.9 μmol/L (HepG2), whereas DOM-1 did not have such an effect. Additionally, NO was decreased (0.84 μmol/L DON), whereas interleukin (IL)-6 was increased (0.42 μmol/L DON) in lipopolysaccharide (LPS)-stimulated DON-, but not DOM-1-treated RAW cells. Tumor necrosis factor (TNF)-α release, however, was not affected. Interestingly, albumin secretion of HepG2 cells was decreased by both DON and DOM-1 but at a much higher concentration for DOM-1 (228 versus 0.9 μmol/L for DON). 98.9% of DOM-1 was retrieved by liquid chromatography tandem mass spectrometry at the end of the experiment, proving its stability. In this study, IL-6 was the most sensitive parameter, followed by NO and albumin release and viability for HepG2 and IPEC-1.     

Ability of bisbenzylputrescine and propanediamine analogs to modulate the intracellular polyamine pool of P388D1 cells

The effects of a series of bisbenzyldiamine analogs have been tested on P388D1 cell line in vitro. Their effects on cell growth, polyamine oxidase (PAO) activity and intracellular polyamine content were determined. The cytotoxicity tests were performed in culture medium supplemented with 100 mol/L aminoguanidine (I), 100 mol/L aminoguanidine and 100 mol/L N,N-bis(2,3-butadienyl)-1,4-butanediamine (MDL 72,527) (II), and finally 100 mol/L aminoguanidine and 200 mol/L D,L-difluoromethylornithine (DFMO) (III). The IC50 values under conditions I and III were similar, suggesting that inhibition of ornithine decarboxylase by DFMO did not affect the biological effect of our derivatives. Spermine and spermidine remained nontoxic in conditions I and III. However in the condition II, the toxicity of all tested compounds (excepted spermidine) was increased, suggesting that the inhibition of cellular PAO increased their toxicity.The enzymatic test of PAO showed that at high doses inhibition of this enzyme by putrescine analogs occurred, while the N-methylated propanediamine derivative increased the enzyme activity; however, these results do not correlate with cytotoxicity tests. When these derivatives were incubated for 48 h with the cells, all of them increased the cell content in putrescine (160%) and spermine (145%) and decreased the spermidine content (75%) without any modification of the total amount of polyamine.The correlation between the cytotoxic results and the intracellular polyamine determination shows that the increase in spermine content along with the inhibition of retroconverting PAO enzyme increases the toxic effect of tested compounds (including spermine), suggesting that spermine toxicity is more important in the absence of intracellular oxidation processes.     

Estradiol as an anti-aromatase agent in human breast cancer cells

Estradiol (E(2)) is an important risk factor in the development and progression of breast cancer. However, a "direct effect" of E(2) in breast cancerization has not yet been demonstrated. The estrogen receptor complex can mediate the activation of oncogens, proto-oncogens, nuclear proteins and other target genes that can be involved in the transformation of normal to cancerous cells. Breast cancer cells possess all the enzymes (sulfatase, aromatase, 17beta-hydroxysteroid dehydrogenase (17beta-HSD)) necessary for the local bioformation of E(2). In the last years, many studies have shown that treatment of breast cancer patients using anti-aromatase agents has beneficial therapeutic effects. The aromatase activity is very low in most breast cancer cells but was significantly increased in a hormone-dependent breast cancer cell line: the MCF-7aro, using the aromatase cDNA transfection and G-418 (neomycin) selection. In the present study, we explore the effect of E(2) on the aromatase activity of this cell line. The MCF-7aro cell line was a gift from Dr. S. Chen (Beckman Research Institute, Duarte, U.S.A.). For experiments the cells were stripped of endogenous steroids and incubated with physiological concentrations of [(3)H]-testosterone (5 x 10(-9)mol/l) alone or in the presence of E(2) (5 x 10(-5), 5 x 10(-7) and 5 x 10(-9)mol/l) for 24h at 37 degrees C. The cellular radioactivity uptake was determined in the ethanolic supernatant and the DNA content in the remaining pellet. [(3)H]-E(2), [(3)H]-estrone ([(3)H]-E(1)) and [(3)H]-testosterone were characterized by thin layer chromatography and quantified using the corresponding standard. It was observed that [(3)H]-testosterone is converted mainly into [(3)H]-E(2) and not to E(1), which suggests very low or absence of oxidative 17beta-HSD (type 2) activity in these experimental conditions. The aromatase activity, corresponding to the conversion of [(3)H]-testosterone to [(3)H]-E(2) after 24h, is relatively high, since the concentration of E(2) was 2.74+/-0.11pmol/mg DNA in the non-treated cells. E(2) inhibits this conversion by 77, 57 and 21%, respectively, at the concentrations of 5 x 10(-5), 5 x 10(-7) and 5 x 10(-9)mol. In previous studies, it was demonstrated that E(2) exerts a potent anti-sulfatase activity in the MCF-7 and T-47D breast cancer cells. The present data show that E(2) can also block the aromatase activity. The dual inhibition of the aromatase and sulfatase activities, two crucial enzymes for the biosynthesis of E(2) by E(2) itself in breast cancer add interesting and attractive information for the use of estrogen therapeutic treatments.     

Single-step, multiple retroviral transduction of human T cells

Background

Retroviral transduction of human peripheral blood T cells has considerable potential in the development of gene therapy strategies for immunological disorders. New vectors and experimental procedures have been developed for efficient transduction of several genes into human T cells.

Methods

Bicistronic retroviral vectors encoding distinct cell markers were used for the simultaneous multiple transduction of a human T‐cell line (MT‐2), as well as of human peripheral blood T cells from normal donors. Transduction efficiencies were evaluated by flow cytometry and double‐ and triple‐transduced cells were isolated by fluorescence cell sorting.

Results

Four new bicistronic retroviral vectors were developed that express different gene markers under the control of the internal ribosome entry site (IRES) of the encephalomyocarditis virus. These markers are, respectively, enhanced green fluorescent protein (EGFP), β‐galactosidase, and truncated versions of human nerve growth factor receptor (ΔNGFR) and human growth hormone receptor (ΔGHR). A single 1 h spinoculation infection, performed in the presence of polybrene and using transiently produced amphotropic retroviral particles, was sufficient to obtain transduction efficiencies consistently greater than 50% on human peripheral blood T lymphocytes which had been previously stimulated for 3 days with immobilized anti‐CD3. The transient production of viral particles encoding EGFP, ΔNGFR, and ΔGHR markers in the same viral supernatant has allowed up to three different genes to be introduced simultaneously into human T cells.

Conclusions

This study describes new experimental conditions for efficient single‐step multiple transduction of human primary T lymphocytes. The procedure could be of interest for the development of gene therapy approaches. Copyright © 2002 John Wiley & Sons, Ltd.

     

Active cell membrane mechanisms involved in the exclusion of RH 123 allow distinction between normal and tumoral cells

Human cell lines derived from three epithelial carcinomas (CaSki, HeLa, SiHa), one B lymphoma (BL60), one promyelocytic (HL60), one monocytic (U937) leukemia, one chronic myelogenous leukemia (sensitive K562S; multichemoresistant K562R) and normal human skin fibroblasts were compared for their capacity of staining with rhodamine 123 (Rh 123) and their kinetics of dye exclusion. Cells were exposed for 30 min to 10 g/ml of Rh 123 in culture medium; fluorescence intensity was measured by flow cytometry immediately or 1, 2, 3 and 4 h after staining. The highest fluorescence intensity was observed in carcinoma cell lines; there was no incorporation in multichemoresistant K562R cells. Exclusion of Rh 123 was evaluated from 0 to 4 h, both by flow cytometry and by fluorimetry. Fluorescence intensity measured by flow cytometry decreased slightly in carcinoma and leukemia cells and rapidly in fibroblasts. In all cell lines Rh 123 exclusion was inhibited by 40 mol/L verapamil and 5 mmol/L probenecid. Thus, incorporation and exclusion of Rh 123 allows distinction between normal and tumoral cells; moreover, inhibition of exclusion by verapamil and probenecid favors the involvement of active cell membrane mechanisms in the exclusion process.Abbreviations PBS phosphate-buffered saline - Rh 123 rhodamine 123     

Paclitaxel probably enhances cytotoxicity of natural killer cells against breast carcinoma cells by increasing perforin production

Paclitaxel, a semisynthetic taxane, is one of the most active chemotherapeutic agents for the treatment of patients with breast cancer. We focused on the effect of paclitaxel on the cytotoxicity of natural killer (NK) cells. NK cells were purified by negative selection with magnetic beads from peripheral blood mononuclear cells of healthy volunteers. A human breast carcinoma cell line BT-474 and an NK cell–sensitive erythroleukemia cell line K562 were used as targets. Cytotoxicity of NK cells was determined by ⁵¹Cr-release assay with labeled target cells. Paclitaxel (1–100 nM) did not affect cellular viability, and significantly enhanced cytotoxicity of NK cells in a dose-dependent manner. Although paclitaxel did not affect Fas-ligand expression of NK cells, paclitaxel induced mRNA and protein production of perforin, an effector molecule in NK cell–mediated cytotoxicity. Concanamycin A, a potent inhibitor of the perforin-mediated cytotoxic pathway, inhibited paclitaxel-dependent NK cell–mediated cytotoxicity. Furthermore, paclitaxel induced activation of nuclear factor B (NF-B) in NK cells. NF-B inhibitor pyrrolidine dithiocarbamate significantly suppressed both paclitaxel-induced perforin expression and NK cell cytotoxicity. Our results show for the first time that paclitaxel enhances in vitro cytotoxicity of human NK cells. Moreover, our results suggest a significant association between enhanced NK cell cytotoxicity, increased perforin production, and NF-B activation.     

Early development of CD8-negative and CD8-positive MHC-unrestricted cytotoxic cells induced by alloantigen inoculation in mice

Peritoneal cells (PC) in C57B1/6 (B6, H-2b) mice receiving an intraperitoneal (i.p.) injection of allogeneic BALB/c (H-2d) spleen cells demonstrated potent cytotoxic activity against syngeneic, xenogeneic, third-party allogeneic tumors as well as H-2d derived tumors. Maximum cytotoxic activity against various tumors other than H-2d derived tumor, B16 (H-2b) was elicited on day 3 post allosensitization and decreased drastically thereafter, whereas cytotoxic activity against P815 (H-2d) peaked 3 days after the inoculation and maintained the peak activity thereafter. Surface phenotype of PC responsible for the cytotoxic activity against B16 was Thy-1+/-, Lyt-2-, L3T4-, asialo GM1 (AGM1)+, and that of PC against P815 was Thy-1+, Lyt-2+ (or Lyt-2+/-), L3T4-, AGM1+. These phenotypes showed similar phenotypes to the counterparts against B16 and against P815 in spleen cells induced by intravenous inoculation of alloantigen. When mice were pretreated i.p. with anti-AGM1 antibody before the allosensitization, anti-P815 cytotoxic-activity in PC was completely diminished. Similar activity in spleen, however, was enhanced by i.v. treatment with the antibody before the i.v. inoculation of alloantigen. The data clearly demonstrate that in vivo inoculation of B6 mice with normal allogeneic cells induces "NK-like" CD8- cytotoxic cells and "anomalous" CD8+ cytotoxic cells in PC.     

重组人脑乙酰胆碱酯酶的基因表达和生化毒理学性质

人脑乙酰胆碱酯酶的全长cDNA序列克隆到真核高效表达载体pcDNA3.1中 ,并将pcDNA AChE转染人胚肾细胞株 2 93细胞 ,进行rhAChE的暂时表达 .真核细胞表达的rhAChE的生化性质与天然人脑AChE十分相似 .rhAChE的Km 值约为 137μmol L ;有过量底物抑制现象 ;可被胆碱酯酶抑制剂huperzineA和eserine抑制 (IC50 分别为 2 5× 10 -8mol L和 1 0× 10 -7mol L) ;肟类化合物HI 6 (10 -4 mol L)可以有效地重活化被sarin(10 -6mol L及 10 -7mol L)抑制的rhAChE ,4h内重活化率分别达 86 %和 97% .rhAChE反复冻融 3次 ,酶活性没有损失 .     

Virulizin, a novel immunotherapy agent, activates NK cells through induction of IL-12 expression in macrophages

Virulizin, a novel biological response modifier, has demonstrated significant antitumor efficacy in a variety of human tumor xenograft models including melanoma, pancreatic cancer, breast cancer, ovarian cancer and prostate cancer. The significant role of macrophages and NK (Natural killer) cells was implicated in the antitumor mechanism of Virulizin where expansion as well as increased activity of macrophages and NK cells were observed in mice treated with Virulizin. Depletion of macrophages compromised Virulizin-induced NK1.1⁺ cell infiltration into xenografted tumors and was accompanied by reduced antitumor efficacy. In the present study, involvement of macrophages in NK cell activation was investigated further. We found that depletion of NK cells in CD-1 nude mice by anti-ASGM1 antibody significantly compromised the antitumor activity of Virulizin. Cytotoxicity of NK cells isolated from Virulizin-treated mice was enhanced against NK-sensitive YAC-1 cells and C8161 human melanoma cells, but not against NK-insensitive P815 cells. An increased level of IL-12 was observed in the serum of mice treated with Virulizin. IL-12 mRNA and protein levels were also increased in peritoneal macrophages isolated from Virulizin-treated mice. Moreover, Virulizin-induced cytotoxic activity of NK cells isolated from the spleen was abolished when an IL-12 neutralizing antibody was co-administered. In addition, depletion of macrophages in mice significantly impaired Virulizin-induced NK cell cytotoxicty. Taken together, the results suggest that Virulizin induces macrophage IL-12 production, which in turn stimulates NK cell-mediated antitumor activity.     

Bispecific-monoclonal-antibody-directed lysis of ovarian carcinoma cells by activated human T lymphocytes

Summary Two different bispecific hybrid antibodies were established by fusing a hybridoma producing monoclonal antibody (mAb) against the pancarcinoma antigen KS1/4 with either of the two hybridomas OKT3 and 9.3, secreting antibodies reactive with the T cell determinants CD3 and CD28, respectively. The KS1/4 antibody reacts with a 40-kDa cell-surface glycoprotein antigen that is expressed on the surface of a variety of adenocarcinoma cells, including ovarian carcinoma. The ability of the bispecific antibodies 9.3KS1/4 and OKT3KS1/4 to direct peripheral blood mononuclear cells (PBMC) specifically against OVCAR-3 ovarian carcinoma target cells was measured in a 4-h⁵¹Cr-release assay. The bispecific antibodies were four to six times more potent in killing the OVCAR-3 target cells when compared to their parental antibodies either alone or in combination. A dose-dependent response was observed in the 10–10000 ng/ml range. The specificity of the targeting was demonstrated by the complete inhibition of cytotoxic activity following pre-incubation of tumor target cells with the parental mAb and by the lack of killing of KS1/4-negative target cell lines. An evaluation of the efficacy of PBMC from ovarian cancer patients as effector cells revealed that their specific cytotoxicity against OVCAR-3 cells was enhanced severalfold by bispecific antibodies as compared to parental antibodies. Furthermore, stimulation of PBMC with immobilized CD3 and interleukin-2 for 4 days resulted in an enhanced directed killing of human ovarian carcinoma cells by human T effector cells and the bispecific antibodies.